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11-09-2011, 12:09 PM - 1 Like   #16
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film to digital

QuoteOriginally posted by Opahujo Quote
I hope it's OK to re-post my question. I have spent many hours reading about DOF, FOV, APS-C, crop factor, etc., and I am beginning to understand most of the differences between film and digital photography, but I still don't know the answer to the above question. Can someone help, please.

My K-r is on order! :-)))
Your Pentax film camera lenses will all fit and function just fine on the Kr. If they are not A lenses, but the old M or K lenses, you will have to photograph on manual, your automatic exposure settings won't work. If you have A lenses and set the aperture ring to "A" you will have most automatic functions (except for auto-focus, of course). Remember there will be a multiplier on your field of view of 1.5. A 50mm lens will have the field of view of a 75mm lens on film. A 35mm lens will have the field of view of a 52.5mm lens on film. etc.

11-10-2011, 05:56 PM   #17
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QuoteOriginally posted by Opahujo Quote
About the S3IS, I looked at the shots of my 8'x14' train layout again and you're right, DoF is not the problem - the focus seems to be uniform - but the details suck, like the writing on the sides of the cars just isn't "crisp." The strange thing is that pictures of a group of people, close-ups for stuff I sell sometimes on e-Bay, or most other uses are fine.
I would agree DOF should not be a problem, the kit lens 18-55 has a wide field of view and large DOF at 18mm when stopped down, and the larger sensor of the Kr will give you a much sharper image with greater detail than the Canon. I also shoot a Canon P&S and indoors the Kr is much better than my 14.7mp Canon SD990. With a long exposure on a tripod using florescent lighting you should be good.

Hans
11-10-2011, 05:57 PM   #18
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QuoteQuote:
Your Pentax film camera lenses will all fit and function just fine on the Kr. If they are not A lenses, but the old M or K lenses...
They are M lenses and one is a 28mm lens. I'm thinking that lens is close to a "Standard" lens (28mm x1.5=42mm). Although it's a manual lens, I like the idea that it has a DoF scale. Please comment.
11-10-2011, 06:11 PM - 1 Like   #19
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I have 2 28's a 42mm with adapter that only works in manual using the green button and a SMC-A 28 f2.8 and it works fine in all exposure modes but is manual focus. If you can get far from the layout the 28 should be fine, if your Kr comes with a kit lens the kit lens would be better. The kit is wider and has a min aperture of f29 so the kit lens at 18mm f29 has a greater DOF than the 28mm at F22

The link below is for a DOF calculator just put in the camera and focal length of lens and it will provide you the DOF in feet. you will have to use the chart for the Kx as it is not updated for the Kr but the results is the same.

According to the chart with the 28 @ f22 if you focus to 6' everything from 3' to infinity will be in focus

Hans

Depth of Field Table


Last edited by hnikesch; 11-10-2011 at 06:17 PM.
11-11-2011, 09:52 AM   #20
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QuoteOriginally posted by hnikesch Quote
I also shoot a Canon P&S...
I'm still curious and for my own edification, the cannon S3IS tends to default to 6mm (as was pointed out to me in a post above) and when then in Av mode set to f8, is the aperture really0.75mm? Or is it electronically manipulated. From film camera experience I seem to recall that 0.75mm is getting into pin hole lens territory.

About your 18-55mm kit lens comments, I'm anxious to give it a workout. My K-r is scheduled to arrive today (UPS, unlike the USPS, delivers today).

I appreciate all the help that you provided. BTW: How do I become more than a "New Member?"
11-11-2011, 01:14 PM   #21
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QuoteOriginally posted by Opahujo Quote
I'm still curious and for my own edification, the cannon S3IS tends to default to 6mm (as was pointed out to me in a post above) and when then in Av mode set to f8, is the aperture really0.75mm? Or is it electronically manipulated. From film camera experience I seem to recall that 0.75mm is getting into pin hole lens territory.
That depends on frame size. If I turn a railway boxcar into a pinhole cam, its pinhole might be 10-20mm across. I gargle for PINHOLE WIKI and find the Wikipedia PINHOLE CAMERA page which says:

QuoteQuote:
Optimally, the size of the aperture should be 1/100 or less of the distance between it and the projected image.
So at the shortest focal length for your S31S (6mm) a pinhole aperture would be 0.06mm or smaller -- WAY beyond the 0.75mm you get at f/8. Yeah, f/100 and beyond is pinhead pinhole territory. NOTE: In my early eBay LBA frenzy, I bought a lens-in-a-cap pinhole that on PK cams is 45mm f/180. THAT is a pinhole!

QuoteQuote:
How do I become more than a "New Member?"
Keep posting for another week or two. It happens fast.

Last edited by RioRico; 11-11-2011 at 01:34 PM.
11-11-2011, 02:30 PM   #22
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QuoteOriginally posted by Opahujo Quote
I'm still curious
My SD series Canon P&S use an internal ND filter to achieve f8 it has an f2.8 lens (@ wide zoom position) so it uses only 2 aperture values and makes it's exposure corrections using shutter speed and ISO values. But this is limited to SD series and real small Canons, I'm sure the S3is has a real aperture.

Hans

Last edited by hnikesch; 11-11-2011 at 02:39 PM.
11-13-2011, 10:20 AM   #23
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Yeah, f/100 and beyond is pinhead pinhole territory.
Got it. Your boxcar example really helped. So, a 50mm lens at F100 in the 35mm world means a pin hole diameter of 0.5 mm - that's not an unreasonable dimension.

Received my K-r yesterday. Although it comes with a 350 -page manual, it is the easiest to operate digital camera that I have ever used. The menus are fantastic and intuitive for the user. My hat's are off to Pentax. I took a shot in the HDR mode of a blackboard with a lunch menu that was next to a window - unbelievable great result compared to an Auto shot! In the latter mode, the whole shot was very dark and no writing on the blackboard was visible.

11-18-2011, 12:33 AM   #24
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i have KR+ A 50MM F1.7 can any suggest me good setting for shooting kids in low light? i tried few in prog mode but results were not good. can any one help me?
11-18-2011, 01:12 AM   #25
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QuoteOriginally posted by ajaya Quote
i have KR+ A 50MM F1.7 can any suggest me good setting for shooting kids in low light? i tried few in prog mode but results were not good. can any one help me?
Tv mode; shutter= 1/50 second; aperture= f/1.7; let the ISO float as high as needed. The Kr is great for high-ISO shooting.
11-18-2011, 01:55 AM   #26
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QuoteOriginally posted by RioRico Quote
Tv mode; shutter= 1/50 second; aperture= f/1.7; let the ISO float as high as needed. The Kr is great for high-ISO shooting.
thanks today i will try and upload photos soon
11-18-2011, 07:04 AM   #27
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I have a K-r with a 50 mm f/1.7 as well. I find that at f/1.7 it is fairly sharp but the DOF is pretty thin at nominal distances (it is only 6" at 8 feet). Therefore, very hard to get an in focus image...especially with moving kids. I usually stop down to f/2.0, f/2.5 or f/2.8. Although I do loose some light (and have to bump my ISO) I get many more photos that are sharp.
11-18-2011, 05:24 PM   #28
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QuoteOriginally posted by ablundon Quote
I have a K-r with a 50 mm f/1.7 as well. I find that at f/1.7 it is fairly sharp but the DOF is pretty thin at nominal distances (it is only 6" at 8 feet). Therefore, very hard to get an in focus image...especially with moving kids. I usually stop down to f/2.0, f/2.5 or f/2.8. Although I do loose some light (and have to bump my ISO) I get many more photos that are sharp.
Yes, I should have advised f/1.7 to f/3.5 or even f/4. Those will have more usable DOF. I get carried away with my CIF performance. If a tighter aperture means boosting ISO a bit more and getting some noise, well, remember that noise can be fixed in PP but motion blur and too-thin DOF can't.
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